Medical leads and related systems that include coiled filars with longitudinally straight ends

ABSTRACT

Medical leads included coiled filars that have longitudinally straight ends. The coiled filars may be coiled at a constant pitch until reaching the point where the filars become longitudinally straight. The coiled filars may reside within a central lumen of the lead body, while the longitudinally straight portions may reside in a region where electrical connectors are present and where filar passageways provide a pathway for the filars to exit the central lumen and bond with the electrical connectors. The coiled filars may be created with longitudinally straight ends using a body that includes longitudinally straight holes that receive the filars and maintain the longitudinally straight configuration while the remaining portion of the filars is being coiled.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 61/319,853, filed Mar. 31, 2010, which application ishereby incorporated by reference as if re-written in its entirety.

TECHNICAL FIELD

Embodiments relate to medical leads and systems that utilize medicalleads. More particularly, embodiments relate to medical leads thatinclude coiled filars that have longitudinally straight ends.

BACKGROUND

Medical leads often include multiple filars that carry electricalsignals between electrical circuitry of medical devices and electrodeson a distal end of the medical leads. The filars extend from connectorson a proximal end of the medical leads to the electrodes on the distalend.

During construction of the medical leads, the filars are initiallyplaced within an interior of a lead body. In many cases, the lead bodyincludes a central lumen and the filars are present within the centrallumen. The filars within the central lumen may be coiled to offerflexibility and extendibility to the lead. The filars must be broughtinto physical contact with the electrical connectors and electrodes onthe proximal and distal ends of the leads. This is largely a manual taskwhere a technician must cut a slit in the lead body, select a filar, andpull the filar through the slit. The filar is then physically attachedto the electrode that is placed over the lead body nearby the slit.

Selecting the filar and pulling it through the slit can be a burdensometask, especially where the filars are coiled within the lead body. Wherethe filars are coiled, the technician must first unwind the filars overa certain length so that the filars can be individually grasped to pullthrough the appropriate slit in the lead body. The more burdensome thetask of assembling the medical leads, the more costly the process interms of the amount of time spent per lead.

Once a medical lead is constructed, it is then used in practice by beinginserted into a medical device by a clinician during the installation ofthe medical device for a patient. When installing the medical lead, theclinician grasps the proximal end and inserts the proximal end into aport of the medical device. The stiffness of the proximal end of thelead affects the amount of insertion force that may be supplied. If theproximal end is not adequately stiff, the clinician may have troubleproperly inserted the lead. However, if the whole lead body is stiff,then routing the lead body to the stimulation site within the patientbecomes difficult and the lead is more susceptible to movement anddamage due to movements of the patient.

SUMMARY

Embodiments address one or more of these issues and others by providinga lead having a coiled filars that have longitudinally straight ends.The coiled filars may be at a constant pitch until reaching a point atwhich the filars become longitudinally straight. Additionally, thecoiled filars may be present within a central lumen of the lead body.The longitudinally straight portions of the coiled filars may be presentwithin a region of the lead where connectors are present and thelongitudinally straight portions may exit the central lumen throughfilar passageways aligned with the connectors so that the filars may bebonded to the connectors.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a medical system including an implantable medical deviceand an implantable medical lead according to various embodiments.

FIG. 2 shows a proximal end of an example of the medical lead example.

FIG. 3 shows the proximal end of the medical lead example with an outerlayer and an outer tubing of the lead body removed to reveal a shield,an inner layer, and an inner tubing.

FIG. 4 shows the proximal end of the medical lead example with an innerlayer of the lead body removed to reveal a coiled set of filars.

FIG. 5 shows the proximal end of the medical lead example with a clinkremoved to reveal the inner tubing of the lead body joining a lumenbody.

FIG. 6 shows the proximal end of the medical lead example with the innertubing removed to reveal the coiled set of filars entering the lumenbody.

FIG. 7 shows the proximal end of the medical lead example with spacersbetween connectors removed.

FIG. 8 shows the proximal end of the medical lead example with theconnectors removed.

FIG. 9 shows the proximal end of the filars of the medical lead example.

FIG. 10 shows the transition of the filars from being coiled to beinglongitudinally straight for the medical lead example.

FIG. 11 shows a longitudinal cross-sectional view of the medical leadexample.

FIG. 12 shows the proximal end of the medical lead during assembly whilethe filars are being exposed to the connectors.

FIG. 13A shows a transverse cross-sectional view of the lumen body forthe medical lead example.

FIG. 13B shows a transverse cross-sectional view of an alternative lumenbody for the medical lead example that includes a stiffener.

FIG. 13C shows a perspective view of the lumen body of FIG. 13B.

FIG. 14A shows a transverse cross-sectional view of a first alternatelumen body that has a sunflower filar lumen design and a stiffener forthe medical lead example.

FIG. 14B shows a perspective view of the lumen body of FIG. 14A withoutthe stiffener.

FIG. 14C shows a perspective view of the lumen body of FIG. 14Aincluding the stiffener.

FIG. 15A shows a transverse cross-sectional view of a second alternatelumen body that has a stiffener for the medical lead example.

FIG. 15B shows a transverse cross-sectional view of an alternativesecond alternate lumen body for the medical lead example that lacks astiffener.

FIG. 15C shows a perspective view of the lumen body of FIG. 15A.

FIG. 16 shows the proximal end of a medical lead example where theproximal ends of the filars are longitudinally straight without a lumenbody being present.

FIG. 17 shows a longitudinal cross-sectional view of the medical leadexample of FIG. 16.

FIG. 18 shows a tool for creating longitudinally straight ends forfilars being coiled.

FIG. 19 shows the example of the tool with an outer cover removed.

FIG. 20 shows a distal end view of the tool with the outer coverremoved.

FIG. 21 shows a side view of the distal end of the tool with the outercover removed.

FIG. 22 shows a distal end view of a main body of the tool with theouter cover removed.

FIG. 23A shows a coiling device that includes either a tool or lumenbody to create longitudinally straight ends for filars being coiled onthe coiling device.

FIG. 23B shows the filars with ends placed through the tool or lumenbody and fixed to a chuck before coiling of the filars begins.

FIG. 23C shows the filars being coiled about a mandril while the ends ofthe coils are maintained in a longitudinally straight configuration by atool or lumen body.

DETAILED DESCRIPTION

Embodiments provide medical leads and related medical systems thatinclude coiled filars with longitudinally straight ends. The coiledfilars with the longitudinally straight ends may be coiled at a constantpitch within the lead body. The coiled filars with the longitudinallystraight ends may be present within the lead such that the coiledportion resides within a central lumen of the lead body.

FIG. 1 shows a medical system 100 that includes an implantable medicaldevice 101 and an implantable medical lead 110, 110′. The implantablemedical device 101 includes a housing 102 that contains circuitry 104for providing medical tasks such as stimulation or physiologicalsensing. The circuitry 104 includes electrical interconnections to afeedthrough 106 that passes the electrical signals to contacts 108within a header block 116 of the medical device 101. The contacts 108are where connectors of the header block 116 contact connectors of themedical lead 110, 110′.

The medical lead includes conductors 112 which are coils in thisexample. These conductors 112 carry signals between the connections 108within the header block 116 and electrodes 114 on a distal end of themedical lead 110, 110′. These electrodes 114 may be used to deliverstimulation signals being generated by the circuitry 104 to adjacenttissue of a patient and/or to sense physiological signals from theadjacent tissue and provide those to the circuitry 104.

FIG. 2 shows a proximal end of an example of the medical lead 110. Thisproximal end is ultimately inserted into the medical device 101 duringinstallation of the medical device 101 and the medical lead 110. Themedical lead 110 includes an outer jacket layer 120 that spans from thedistal end of the lead up to this proximal end as shown. In thisparticular example, the medical lead 122 also includes an outer tubing122 that forms a lap joint with inner layers for examples of the medicallead 122 that are shielded so as to be conditionally safe for exposureto magnetic resonance imaging (MRI) scans.

A clink 124 is present on the proximal end and abuts the outer tubing122 of the lead body. For embodiments where a tap joint is not neededsuch as because a shield is not present, the outer jacket layer 120 mayabut the clink 124 directly. The clink 124 is the final electricalconnector that is inserted into the header block 116 of the medicaldevice 101 and may contact seals within the header block 116 to seal theport within the header block 116 that has received the proximal end ofthe lead 110.

Proximal to the clink 124 are insulative spacers 136, 138, 140, and soon. These insulative spacers separate each of the electrical connectors128, 132 and so on that are present. The electrical connectors 128, 132make contact with the electrical contacts within the header block 116.

The proximal clink 124; insulative spacers 136, 138, and 140; and theelectrical connectors 128, 132 are all placed on a lumen body 148 thatextends to the proximal tip of the lead 110. The lumen body 148 containsmultiple filar lumens 152 and also includes a central lumen 150 that mayreceive a stylet when the lead is being routed to the stimulation siteprior to insertion into the header block 116. The proximal clink 124;insulative spacers 136, 138, and 140; the electrical connectors 128,132, and the lumen body 148 are all discussed in more detail below.

FIG. 3 shows the proximal end where the lead body encounters the distalend of the clink 124. In this view, the outer tubing 122 and outerjacket layer 120 have been removed to reveal a braided shield 142 thatis wrapped about an inner jacket layer 144. In this example where a lapjoint is present at the termination of the shield 142, an inner tubing146 of the lead body extends from the inner jacket layer 144 into theclink 124. For other embodiments such as those where a shield is notpresent, the inner jacket layer 144 may be integral with the outerjacket layer 120 such that the jacket as a whole enters the clink 124.

FIG. 4 shows the proximal end with the shield 142 and the inner jacketlayer 144 removed to reveal coiled filars 112 entering the inner tubing146 which is partially contained within the clink 124. This viewillustrates that the clink 124 has a proximal slot 126 where a filar canbe received and connected via a weld or other form of attachment. Thisview also illustrates that the electrical connectors 128, 132 which arelongitudinally spaced also have distal slots 130, 134 where a filar canbe received and connected via a weld or other form of attachment. As canbe seen, the slots 126, 130, and 134 are offset circumferentially fromeach other about the proximal end.

FIG. 5 shows the proximal end with the clink 124 removed to reveal theinner tubing 146 of the lead body abutting the distal end of the lumenbody 148. As noted above, the outer tubing 122 of the lead body residesover the abutment of the inner tubing 146 to the lumen body 148 andoverlaps the end of the clink 124. In examples where a lap joint is notpresent, then the jacket layer(s) 120, 144 of the lead body may abutand/or overlap with the lumen body 148.

FIG. 6 shows the proximal end with the inner tubing 146 removed toreveal the coiled filars 112 continuing to the distal end of the lumenbody 148 where the filars then enter the lumen body 148. At that point,each filar 112 enters a filar lumen 152 and extends in the proximaldirection in a longitudinally straight configuration.

FIG. 7 shows the proximal end of the lead 110 with the spacers 136, 138,140 and so on removed to reveal the lumen body 148 between each of theelectrical connectors 128, 132. Each electrical connector 128, 132 isaligned so that the slot 130, 134 of the electrical connector is alignedwith a corresponding filar passageway 154, 156 within the lumen body148. Each filar passageway 154, 156 provides a pathway for a filar 112to exit the particular filar lumen 152 that it resides within and enterthe slot 154, 156 of the appropriate electrical connector 128, 132 towhich the filar should be electrically connected. The filar passageway154, 156 may be a slit made by a knife or other cutting manualinstrument or may be a hole that has been punched, laser ablated, orotherwise created. Each filar passageway 154, 156 is created inalignment with each corresponding filar lumen 152 such that the filarpassageways 154, 156 are offset both longitudinally andcircumferentially.

FIG. 8 shows the proximal end of the medical lead with the electricalconnectors 128, 132, and so on removed to fully reveal the lumen body148. As is discussed below, the assembly of the lead 110 may begin afterthe filars 112 have been coiled in a process that utilizes the lumenbody 148 to create longitudinally straight filar ends. In that case, theconstruction of a subassembly of the coiled filars 112 with thelongitudinally straight ends present within the filar lumens 152 of thelumen body 148 as shown in FIG. 8 occurs during the filar coilingprocess, and this subassembly may then be carried forward to the leadassembly process.

As can be seen in this example, the lumen body 148 may have a lengththat spans the clink 124 and all connectors on this end of the medicallead 110. As such, the lumen body 148 is a relatively small lengthcompared to the length of the whole medical lead 110 and is much lessthan half the length of the whole lead 110 in this example. The lengthof the lumen body 148 in this example is such that the majority of thelumen body 148 is present within the header block 116 upon insertion ofthe lead 110 into the medical device 101. Therefore, the stiffness addedby the lumen body 148 affects only the end region of the lead 110 anddoes not hinder the routing of the lead to the stimulation site.

FIG. 9 shows the proximal end of the filars 112 having longitudinallystraight ends 160. In the medical lead 110, these longitudinallystraight ends 160 are present within the filar lumens 152 of the lumenbody 148. In an alternative medical lead 110′ that is discussed in moredetail below, these longitudinally straight ends 160 may be presentwithin a central lumen of the lead body rather than within filar lumensof the lumen body 148.

FIG. 10 shows a side view of the filars 112 having the longitudinallystraight ends. In this view, it can be seen that the filars are coiledat a constant pitch from a coil starting point at the distal end untilreaching a coil end point where the filars transition into thelongitudinally straight configuration. This transition may be achievedby use of the lumen body 148 during the coiling process. A coiling tooldiscussed in more detail below may be used during the coiling process inplace of the lumen body 148 for the medical lead embodiments 110′ wherethe lumen body 148 is not present or where it is otherwise not desirableto use the lumen body 148 during the coiling process.

FIG. 11 shows a longitudinal cross-sectional view of the medical leadembodiments 110, with the view being stretched in the transversedirection of the lead to more clearly illustrate the details ofconstruction. This view shows that the lumen body 148 includes a filarpassageway 153 aligned with the slot 126 in the clink 124 to allow oneof the filars to exit a filar lumen 152 and connect with the clink 124.In this example, it can be seen that the clink 124 includes a threadedengagement to the inner tubing 146. In this example, the clink 124 alsoincludes a radially extending circumferential flange 125 which abuts theouter tubing 122 as shown.

FIG. 12 shows a view of the proximal end during construction. At thispoint, the individual filars such as filars 112A and 112B are beingpulled through the filar passageways 154, 156 and slots 126, 130 forattachment to the clink 124 and electrodes 128 and so on. With the endsof the filars already being longitudinally straight, the technicianmerely pulls a filar already present at a given filar passageway throughthe slot 126, 130 in the clink 124 or electrode 128 and then creates thebond via a weld or other form of attachment. The technician is relievedfrom having to unwind the coil and select a particular filar among thegroup of unwound filars.

Prior to reaching this point of assembly shown in FIG. 12, the medicallead example 110 may be constructed by starting with a lead body wherethe outer jacket 120 has been ablated to reveal the shield 142 and innerjacket layer 144. A gage pin or stylet may be inserted into the lumenprovided by the inner jacket 144 of the lead body, and the inner tubing146 is placed onto the gage pin and slid into place where the innertubing 146 is bonded to the inner jacket layer 144.

The outer tubing 122 that provides the lap joint is then placed onto thegage pin and slid into place over the exposed shield 142 and innertubing 146. The coiled filars 112 with the ends located within the lumenbody 148 are then placed onto the gage pin and slid into the lumen ofthe lead body provided by the inner jacket 144 until the lumen body 148abuts the inner tubing 146. The inner tubing 146 is bonded to the lumenbody 148.

Then the clink 124 is placed onto the lumen body 148 and slid into placewith the outer tubing 122 overlapping a shoulder of the clink 124. Theclink 124 may be rotated as necessary to align the slot 126 with thefilar passageway 153. The first filar 112A is then pulled through thefilar passageway 153 with the filar 112A being cut to length with theexcess being pulled from the nearest end, in this case from the proximalend. The filar 112A is then bonded to the clink 124.

In some embodiments, the spacer 136 may then be put in place over thelumen body 148 and positioned so that the spacer 136 abuts the clink124. The spacer 136 may be a pre-formed tubing that is slid onto thelumen body 148 and then reflowed at some time after an adjacentconnector 128 is placed onto the lumen body 148 to abut the spacer 136.

In such embodiments, after the spacer 136 has been slid into place, thesubsequent connector 128 is slid into place and is rotated as necessaryto align the slot 130 with the filar passageway 154. The filar 112B forthat electrode is pulled through the filar passageway 154 and slot 130,is cut to length, the excess is pulled from the nearest end, and thefilar 112B is bonded to the electrode 128. The next spacer 138 is thenput into position adjacent the connector 128 and this continues untilall connectors and spacers have been installed. The reflow of theseveral spacers may occur once all of the spacers and connectors areinstalled.

As an alternative embodiment to reflowing spacers pre-formed fromtubing, the spacers 136, 138, 140 and so on may instead be injectionmolded onto the lumen body 148. Here, the clink 124 and all connectors128, 132 and so on may be first installed, and then the gaps betweenthem filled by the injection molding process to create the spacers 136,138, 140 and so on. Furthermore, the injection molded spacers 136, 138,140 and so on may be reflowed after injection molding to ensure that thespaces between electrodes are satisfactorily filled.

FIGS. 13A-13C show one variation for the lumen body. Here, a lumen body304 may be created within filar lumens 306 of a circular cross-sectionand a central lumen 308. The lumen body 304 is surrounded by a layer 302that may represent either a connector or a spacer of a medical lead. InFIG. 13A, a stiffener 310 may be inserted within the central lumen 308with the stiffener being a stiffening tube to maintain the central lumen308 for passage of a stylet. The stiffener 310 may be included toprovide additional stiffness for the end of the lead where the stiffnessadded by the presence of the lumen body 304 is less than desired. Forinstance, the lumen body 304 may be constructed of materials such as 55Shore D or 75 Shore D biocompatible polymers like thermoplasticpolyurethane (TPUR) while the stiffener 310 may be constructed of astiffer material like 99 Rockwell M or 126 Rockwell M biocompatiblepolymer like polyetheretherketone (PEEK).

In FIG. 13B and the perspective view of FIG. 13C, the lumen body 304 mayprovide adequately additional stiffness to the end of the lead for agiven application so that no stiffener is necessary. Here, the lumenbody 304 may also be constructed of materials such as 55 Shore D or 75Shore D biocompatible polymers TPUR.

FIGS. 14A-14C show another variation for the lumen body. Here, a lumenbody 404 may be created within filar lumens 406 with a non-circularcross-section so as to create a sunflower cross-section together with acentral lumen 408 as shown in FIG. 14B. The lumen body 404 is surroundedby a layer 402 that may represent either a connector or a spacer of amedical lead.

As shown in FIGS. 14A and 14C, a stiffener 410 may be inserted withinthe central lumen 408 with the stiffener being a stiffening tube tomaintain the central lumen 408 for passage of a stylet while creating abarrier to isolate each individual filar lumen 406 from the centrallumen 408. Like the example of FIG. 13A above, the lumen body 404 may beconstructed of materials such as such as 55 Shore D or 75 Shore Dbiocompatible polymers like TPUR while the stiffener 410 may beconstructed of a stiffer material like 99 Rockwell M or 126 Rockwell Mbiocompatible polymer like PEEK.

FIGS. 15A-15C show another variation for the lumen body. Here, a lumenbody 204 may be created with fewer but larger filar lumens 206 and acentral lumen 208. In such a case multiple filar ends may be presentwithin a single filar lumen 206. These filar ends that are groupedwithin a filar lumen 206 may be longitudinally straight and may becreated by using a coiled process and coiling tool discussed below. Thelumen body 204 is surrounded by a layer 202 that may represent either aconnector or a spacer of a medical lead. In FIG. 15A, a stiffener 210may be inserted within the central lumen 208 with the stiffener 210being a stiffening tube to maintain the central lumen 208 for passage ofa stylet. Like the example of FIG. 13A above, the lumen body 204 may beconstructed of materials such as such as 55 Shore D or 75 Shore Dbiocompatible polymers like TPUR while the stiffener 210 may beconstructed of a stiffer material like 99 Rockwell M or 126 Rockwell Mbiocompatible polymer like PEEK.

In FIG. 15B and the perspective view of FIG. 15C, the lumen body 204 maybe adequately stiff for a given application so that no stiffener isnecessary. Like the example of FIG. 13B above, here the lumen body 204may also be constructed of materials such as 55 Shore D or 75 Shore Dbiocompatible polymers like TPUR.

While the discussion above regarding the lumen body has been primarilywith respect to the proximal end of the medical lead 110, it will beappreciated that the lumen body may additionally or alternatively belocated at the distal end, where the discussion of connectors 128, 132and so on applies to the electrodes of the distal end. The filars 112may enter the filar lumens 152 of a lumen body 148 present at the distalend, and these filars 112 may have longitudinally straight distal endswithin the lumen body 148.

FIGS. 16 and 17 show views of the medical lead 110′ which is an exampleof medical lead embodiments that lack a lumen body altogether. Thesealternate medical lead embodiments such as the medical lead example 110′have a lead body layer, such as the inner tubing 146′ as shown for thelead 110′ or a continuation of the inner jacket layer 144, thatcontinues to the tip of the lead. The filars 112 transition to alongitudinally straight configuration at the clink 124 so that thelongitudinally straight portion 160 of the filars are present within acentral lumen of the lead body layer such as a central lumen 150′ of theinner tubing 146′.

As can be seen in FIG. 17, the remainder of the lead is the same. As theclink 124, connectors 128, 132, and so on are located on the innertubing 146′ of this example, the inner tubing 146′ includes the filarpassageways 153, 154, 156, and so on discussed above in relation to thelumen body of the previous medical lead example 110. Thus, theconstruction process for this medical lead example 110′, including theprocess of connecting filars 112 to the clink 124 and connectors 128,132, and so on proceeds in the same manner as discussed above, albeitwithout the step of abutting the lumen body 148 to the inner tubing146′. Instead, the coiled filars 112 are placed within the lead bodylumen 150′ an that the longitudinally straight portions 160 are presentwithin the inner tubing 146′. The technician then pulls each filar fromthe central lumen 150′ of the lead body and through the correspondingfilar passageway to the corresponding clink 124 or connector 128, 132.

For medical lead embodiments that may include straight filar ends to acoiled set of filars but lack a lumen body, a lumen tool 500 such as theexample shown in FIGS. 18-22 may be used during a coiling process.Furthermore, for medical lead embodiments that may include straightfilar ends of a coiled set of filars and include a lumen body but do notuse the lumen body during the coiling process, the lumen tool 500 may beused in place of the lumen body during the coiling process.

The lumen tool 500 is used to hold the ends of the filars being coiledin a longitudinally straight and circumferentially spaced arrangementwhile the remainder of each filar is coiled. The lumen tool 500 includesan outer body 502, an inner body 506 surrounded by the outer body 502,and one or more end caps 504, 520. The outer body 502 holds the end caps504, 520 to the inner body 506 such as by a press fit within the outerbody 502. The outer body 502 of this particular example may beconstructed of a variety of materials including any metal or plasticthat has adequate strength to retain the inner body 506 and end caps504, 520.

The end caps 504, 520 may be made of a relatively soft material such aspolyacetal while the inner body 506 may be made of a more rigid materialthat resists twisting during coiling, such as aluminum. The endcap 504includes a set of holes 514 that correspond to the desired location ofeach filar. The endcap 504 also includes a center lumen 516 that canreceive a mandril of a coiling machine, which is discussed below inrelation to FIGS. 23A-C. The relatively soft material for the end caps504, 520 allows the filars 112 to experience less stress where the filmspass into the holes 514.

Each individual filar 112 is inserted into a corresponding hole 514. Thefilar may have a relatively small diameter such as on the order of0.0035 inches while the hole 514 may also have a relatively smalldiameter such as on the order of 0.004 to 0.0045 inches. Thus, passingthe filar 112 directly into the corresponding hole 514 may be difficult.

To ease this insertion process, the end cap 504 may include a series ofradial spines 510, 512 that provide surfaces parallel to thelongitudinal axis of the tool 500 while also defining a wedged shapedsurface 518. The wedged shaped surface 518 may be sloped in thelongitudinal direction. In this manner, each wedge shaped surface 518funnels down to a particular hole 514. Thus, the filar 112 may bedirected toward the wedge shaped surface 518 which is a much largertarget than the hole 514, and the wedge shaped surface 518 together withthe radial spines 510, 512 funnel the filar 112 into the hole 514.

The inner body 506 may be relatively lengthy compared to the diameter ofthe hole 514. Furthermore, the inner body 506 includes filar holes 522and a central lumen 517 that align with the holes 514 and central lumen516 of the end caps 504, 520. These filar holes 522 and central lumen517 run the length of the inner body 506. Creating the inner body 506from a relatively rigid material such as a metal may require that theholes 517 and 522 be made in the body 506 in a manner other thandrilling. To ease this manufacturing process, the inner body 506 mayinclude radial slots 508 that lead to the holes 522.

As can best be seen in FIG. 22, these radial slots 508 may be created byan electrical discharge machining (EDM) process. The radial slots 508are cut during EDM so that a cutting wire of the EDM process may bemoved radially inward through the body 506 in order to ultimatelymachine the holes 522. Furthermore, one of the slots 508 may continueradially beyond the filar hole 522 to further machine the central lumen517.

An alternative construction of the inner body 506 may mimic the lumenbody 404 of FIG. 14C. In this case, a hypotube is press fit into acentral lumen of the inner body 506 to complete the formation of theholes 522.

FIGS. 23A-23C illustrate one example of a coiling process and system 600that may be used to created coiled filars with longitudinally straightends. This system includes a chuck 604 and a mandril 602 where rotationoccurs between the chuck 604 and mandril 602 relative to filar spoolswhile filars are fed onto the mandril 602 from the filar spools. Forsets of filars that are coiled end-to-end such as for conventionalmedical leads, the filars may be attached to the chuck 604 and are thendirectly fed onto the mandril 602 creating a coil that startsimmediately. However, for embodiments of the medical leads 110, 110′that include filars 112 with longitudinally straight ends, either thelumen body 148 or the tool 500 are positioned on the mandril 602adjacent the chuck 604.

Once the lumen body 148 or tool 500 is positioned on the mandril 602,each filar 112A, 112B, 112C and so on is inserted into a correspondingfilar lumen of the lumen body 148 or a filar hole 514 of the endcap 504of the tool 500. Each filar is fed through the lumen body 148 or tool500 until exiting at the chuck 604 where the end of each filar may thenbe secured. Rotation is then created for the combination of the chuck604, lumen body 148 or tool 500, and the mandril 602 relative to thefilars 112A, 112B, 112C, and so on as these filars are fed from wirespools onto the mandril 602. The filars 112A, 112B, 112C and so on arethereby coiled about the mandril 602 while the portions of the filars112A, 112B, 112C and so on that are present within the lumen body 148 ortool 500 are maintained with a longitudinally straight configuration.

Once the coiling is complete the coiled filars 112A, 112B, 112C and soon may be removed from the chuck 604 and mandril 602 such as byreleasing the coils from the chuck 604 and sliding them off of a freeend of the mandril 602. In the case where the lumen body 148 has beenused in the coiling process, the lumen body 148 may be removed togetherwith the filars by also sliding the lumen body 148 off of the free endof the mandril 602 while maintaining the longitudinally straight ends ofthe filars in place within the lumen body 148. The medical lead 110 maythen be constructed as discussed above.

In the case where the tool 500 has been used in the coiling process, thefilars may be released from the chuck 604 and slid off of a free end ofthe mandril 602 while the tool 500 remains in place on the mandril 602.The filars slide out of the holes 514 of the tool and havelongitudinally straight ends that are otherwise uncontained until theyare installed within the lead body. As an alternative, the tool 500 maybe removed from the mandril as the filars are removed, and then thefilars may be removed from the tool 500. The tool 500 may then be reusedto create coiled filars with straight ends for another lead.

While embodiments have been particularly shown and described, it will beunderstood by those skilled in the art that various other changes in theform and details may be made therein without departing from the spiritand scope of the invention.

1. A method of creating a collection of coiled filars withlongitudinally straight ends for a medical lead, comprising: feedingends of the filars through longitudinally extending holes of a body, thebody being mounted to a mandril that is fixed to a chuck; attaching theends of the filars that exit the longitudinally extending holes of thebody to the chuck; feeding the filars onto the mandril as the mandril,body, and chuck rotate to coil the filars about the mandril while theends of the filars remain longitudinally straight within thelongitudinally extending holes of the body; and freeing the filars fromthe chuck and removing the filars from the mandril.
 2. The method ofclaim 1, further comprising removing the filars from the longitudinallyextending holes of the body.
 3. The method of claim 1, wherein feedingthe filars onto the mandril as the mandril rotates comprises coiling thefilars to create a constant pitch.